The present invention relates to an apparatus for removing soot or particulates from the exhaust gases of an internal combustion engine, in particular a Diesel engine. The apparatus includes a metallic housing with inlet and outlet connectors for the exhaust gas flow, and a filter insert that is disposed in the housing and contains a non-metallic, high-temperature-resistant filter means in the form of a wrap structure mounted on a support member, with the filter insert, in the filter housing, separating an untreated-gas chamber from a clean-gas chamber, and an electric current source being used to burn off, in a controlled manner, the soot deposited on the filter means; for this purpose the filter insert is provided with an appropriate electrode configuration.
An apparatus of this general type is described in applicant's copending U.S. patent application, Ser. No. 069,609 Henkel, filed July 2, 1987, belonging to the assignee of the present invention. In that apparatus, surface filters are used that are produced by winding or wrapping a perforated tubular member with a dense quartz glass or ceramic fiber fabric, which has an orthogonal fiber structure. In this connection, wire electrodes wound in a double helix are used for fixing the fabric winding and for introducing the electrical auxiliary energy into the layer of soot deposited on the winding surface over which the flow passes. In this case the soot itself acts as an electrical heat conductor.
The production of surface filters of this type (in particular of the electrode configuration) is very expensive. In addition, a deposition of soot occurs that is not optimum.
It is therefore an object of the present invention, in the case of the surface filter of the type described above, on the one hand to provide a design of the electrode configuration that is less expensive to produce, and on the other hand to produce a very high degree of soot deposition.